Abrasive, a method of polishing with the abrasive, and a method of washing a polished object

ABSTRACT

An abrasive includes abrasive grains, a solvent, and an additive. MnO 2 , Mn 2 O 3 , Mn 3 O 4 , MnO or a mixture thereof as the abrasive grains, H 2 O 2  as the solvent, and HNO 3 , an organic acid, H 2 O 2 , etc., as the additive are employed. The abrasive is solidified with cooling, etc. The abrasive and the additive can be supplied to a polishing apparatus through separate routes.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is based on Japanese priority applicationNo.2002-146126 filed on May 21, 2002, the entire contents of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention generally relates to an abrasive and apolishing method, and in particular, relates to an abrasive and apolishing method that are used in a chemical mechanical polishing (CMP)process in a fabrication process for a semiconductor device.

[0004] 2. Description of the Related Art

[0005] In a semiconductor device and a thin-film magnetic head, etc., amulti-layer structure provided by laminating films that are made bethinner by rolling has been employed. In particular, a multi-layerwiring structure has been employed in a semiconductor integratedcircuit, in which wiring structures obtained by embedding a wiringpattern into an interlayer insulation layer formed on a substrate arelaminated to be a multi-layer. In recent years, much more lamination andintegration have been required with miniaturization of semiconductorintegrated circuits.

[0006] Accordingly, when the multi-layer wiring structure is formed, acontact hole or a wiring slot is conventionally formed on the interlayerinsulation layer and a metal layer is deposited on such an interlayerinsulation layer so that the contact hole or the wiring slot isembedded. Then, such a metal layer is eliminated by means of polishinguntil the surface of the interlayer insulation layer is exposed, so thata flat wiring structure is formed. Since the upper principal surface ofsuch a wiring structure is flat, a next wiring structure is easilyformed thereon.

[0007] Speeding up as well as integration and miniaturization ofsemiconductor integrated circuits has been required. As the width ofwiring is narrowed or the space of wiring is miniaturized for improvingthe integration, both wiring resistance (R) and wiring capacitance (C)are increased. Then, since the transmission time of a signal passingthrough the wiring is proportional to the product of R and C, RC delayoccurs. While the length of the wire is shortened and the throughputspeed of a semiconductor device is thus improved, the RC delay hasbecome problematic in the total circuit delay of the semiconductorintegrated circuit.

[0008] For improving the RC delay, the development of a dual damasceneprocess using Cu (Cu dual damascene process) for a wiring material hasbeen advanced in order to reduce the wiring resistance. In the dualdamascene process, a slot for wiring and a contact hole for interlayerconduction are formed integrally in the interlayer insulation layer. Themetal layer is deposited so that the slot and the contact hole areembedded with the wiring material. The metal layer is eliminated bymeans of polishing until the interlayer insulation layer is exposed, sothat a flat wiring structure is formed. Additionally, in order to reducethe wiring capacitance, conventionally, SiO₂ is used for the interlayerinsulation layer and an organic thermosetting resin with alow-dielectric constant (low-k) has been examined.

[0009] In the polishing process, both the polishing and the eliminationof the metal layer used for wiring, etc., are performed in a CMP(chemical mechanical polishing) method.

[0010] In Japanese Laid-Open Patent Application No. 2000-091284, theinventors of the present invention disclose that an abrasive includingabrasive grains of MnO₂ and an additive that contains NO₃ has aselectivity such that W, Cu, and TiN, etc., as wiring materials can bepolished with little polishing of SiO₂ as the interlayer insulationlayer in the semiconductor device. In such a polishing process, aprocess for adjusting the surface of a polishing cloth by using a dressjig is employed in order to improve the flatness of an object to beprocessed. In the dress jig, a fixed grindstone is used in whichabrasive grains such as diamond, etc. are fixed with resin or epoxy. Theinventors of the present invention found that the problem occurs thatMnO₂ as abrasive grains to polish the semiconductor device dissolves theresin or epoxy, and the abrasive grains of diamond, etc., detached fromthe fixed grindstone, are mixed with the abrasive on the surface of thepolishing cloth, so as to damage the object to be processed.

[0011] The inventors also found that a problem occurs that sincemanganese oxides such as MnO, MnO₂, Mn₂O₃ and Mn₃O₄ have oxidativeeffect, when an additive for eliminating oxides formed on the surface ofan object to be processed is not contained in the abrasive, a metal oran intermetallic compound thereof as an object to be processed isoxidized during the polishing and an oxide layer is formed on thesurface of the object to be processed, so that the object to beprocessed cannot be polished.

[0012] On the other hand, the materials used for the semiconductordevice have been gradually diversified. For the wiring, W, Al, Cu, TiN,Ti, WN, Ta, TaN, etc., are used. Additionally, as a gate electrode, ametal or metal compound electrode could be realized from the requirementto lower the resistance of the electrode. In dual gate CMOS-typesemiconductor devices, selected are different materials for gateelectrodes suitable for P-channel MOS-type semiconductor devices andN-channel MOS-type semiconductor devices, respectively. FIG. 1 is adiagram showing examples of the materials for the gate electrodes. It isconsidered that a material having a work function close to a workfunction (an ideal value) suitable for the respective semiconductordevice should be selected. Then, in the fabrication process, the gateelectrode or wiring in which the above-mentioned metals are used ispolished by a CMP method in the fabrication process of the semiconductordevice. Accordingly, the problem occurs that abrasive grains suitablefor the respective metals are used in the polishing process and variouskinds of abrasive grain components are contained in the waste producedin the process, so that it becomes difficult to treat, recover andrecycle the waste.

[0013] Additionally, in the polishing process, silica (SiO₂) , ceria(CeO₂) , alumina (Al₂O₃), zirconia (ZrO₂) , a manganese oxide, diamond,etc. mainstream in the CMP method at present, are employed as freeabrasive grains and the amount of abrasive grains that contributes tothe polishing effectively is equal to or less than 5% of feed. Also,since abrasive grains that do not contribute to the polishing are wastedwithout being recycled, the amount of the waste becomes too much and aproblem from the viewpoint of effective use of resources occurs.However, from the viewpoint of efficient use of the abrasive grains,techniques for a fixed grindstone in which abrasive grains of manganeseoxide are fixed with a binder are disclosed in Japanese Laid-Open PatentApplication No. 11-207632, Japanese Laid-Open Patent Application No.2000-6031, and Japanese Laid-Open Patent Application No. 2001-9731. Sucha fixed grindstone has the effect that almost all the abrasive grainscontribute to the polishing so as to reduce the amount of the waste.However, it is cumbersome and complicated to adjust the condition of thepolishing because of a lack of uniformity in the abrasive grainsembedded in the fixed grindstone, variation with time in regard to theability of the polishing, and the dispersion of the polishing propertyamong the individual fixed grindstones, etc. Thus, the productionefficiency is lowered and polishing with a fixed grindstone has not yetbecome a technique to replace to polishing with free abrasive grains.

[0014] Furthermore, in Japanese Laid-Open Patent Application No.9-22888, the inventors disclose that after polishing by using theabrasive grains of MnO₂, the semiconductor device is washed by using aninorganic acid such as HCl, HNO₃, H₂SO₄, HF, etc., and H₂O₂ so as toeffectively eliminate MnO₂ remaining in the semiconductor device.However, in a part of the washing condition, the problem occurs thatwiring of Cu or Al embedded in the semiconductor device is corroded bythe washing.

SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to provide an abrasivehaving selectivity for polishing an object to be processed and beingcapable of preventing the object from being damaged and a polishingmethod of polishing the object with the abrasive.

[0016] Another object of the present invention to provide a polishingmethod of polishing an object to be processed with an abrasive, capableof polishing various metals and intermetallic compounds thereof as theobject and treating waste produced by the polishing process easily.

[0017] Yet another object of the present invention is to provide awashing method of washing an object polished with an abrasive, capableof washing away abrasive grains of the abrasive remaining on thepolished object.

[0018] One of the above objects of the present invention is achieved byan abrasive including abrasive grains selected from the group includingMnO, Mn₃O₄, and a mixture thereof and an additive that includes NO₃ ⁻.

[0019] One of the above objects of the present invention is alsoachieved by an abrasive including abrasive grains selected from thegroup including MnO, Mn₂O₃, Mn₃O₄, and a mixture thereof and an additivethat includes H₂O₂.

[0020] One of the above objects of the present invention is alsoachieved by an abrasive including abrasive grains selected from thegroup including MnO, MnO₂, Mn₂O₃, Mn₃O₄, and a mixture thereof and anadditive that includes at least one organic acid selected from the groupincluding gluconic acid, ortho-methylbenzoic acid, citric acid, malonicacid, and acetic acid.

[0021] One of the above objects of the present invention is alsoachieved by a polishing method of polishing an object with an abrasivethat includes abrasive grains, including the step of mixing an additivewith the abrasive, wherein the abrasive grains are selected from thegroup including MnO, Mn₂O₃, Mn₃O₄, and a mixture thereof and theadditive includes NO₃ ⁻.

[0022] One of the above objects of the present invention is alsoachieved by a polishing method of polishing an object with an abrasivethat includes abrasive grains, including the step of mixing an additivewith the abrasive, wherein the abrasive grains are selected from thegroup including MnO, MnO₂, Mn₂O₃, Mn₃O₄, and a mixture thereof and theadditive includes H₂O₂.

[0023] One of the above objects of the present invention is alsoachieved by a polishing method of polishing an object with an abrasivethat includes abrasive grains, including the step of mixing an additivewith the abrasive, wherein the abrasive grains are selected from thegroup including of MnO, MnO₂, Mn₂O₃, Mn₃O₄, and a mixture thereof andthe additive includes an organic acid.

[0024] In the above polishing method, the organic acid may be at leastone organic acid selected from the group including gluconic acid,ortho-methylbenzoic acid, citric acid, malonic acid, and acetic acid.

[0025] In the above polishing methods, the object is selected from thegroup including Si, W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO,MO₂N, Ru, RuO, Pd, Hf, Ta, TaN, WN, Ir and IrO.

[0026] One of the above objects of the present invention is alsoachieved by a polishing method of polishing an object, including thesteps of solidifying an abrasive that includes abrasive grains selectedfrom the group including MnO, MnO₂, Mn₂O₃, Mn₃O₄, and a mixture thereofand polishing the object with the solidified abrasive.

[0027] In the above polishing method, the step of solidifying theabrasive may include cooling and coagulating of the abrasive.

[0028] In the above polishing methods, the abrasive may include anadditive and the additive may include NO₃ ⁻, potassium phthalate, or anorganic acid.

[0029] In the above polishing methods, the abrasive further includes anadditive that includes an inorganic acid, potassium phthalate, anorganic acid, or H₂O₂.

[0030] In the above polishing methods, the object may be SiO₂ orpolysilicon.

[0031] In the above polishing methods, the object may be selected fromthe group including W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO,Mo₂N, Ru, RuO, Pd, Hf, Ta, TaN, WN, Ir and IrO.

[0032] One of the above objects of the present invention is alsoachieved by a washing method of washing an object polished with anabrasive that includes abrasive grains selected from the group includingMnO, MnO₂, Mn₂O₃, Mn₃O₄, and a mixture thereof, wherein the polishedobject is washed with a washing liquid that includes an organic acid ora lower alcohol.

[0033] In the above washing method, a temperature of the washing liquidmay be equal to or more than 50° C.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other objects, features and advantages of the present inventionwill become more apparent from the following detailed description whenread in conjunction with the accompanying drawings, in which:

[0035] FIGS. 1 (A) through (C) are tables showing examples of materialsfor gate electrodes;

[0036] FIGS. 2 (A) through (I) are diagrams illustrating a process offabricating a semiconductor device having a multi-layer wiring structureaccording to the embodiment of the present invention;

[0037]FIG. 3 is a schematic diagram showing the structure of a polishingapparatus;

[0038]FIG. 4 is a table showing the result of test example 5;

[0039]FIG. 5 is a schematic diagram showing the structure of a polishingapparatus;

[0040]FIG. 6 is a table showing the result of test example 6;

[0041]FIG. 7 is a table showing the conditions of samples of abrasivesfor test example 7;

[0042]FIG. 8 is a table showing the result of test example 7 (in thecase of an object to be processed being Cu);

[0043]FIG. 9 is a table showing the result of test example 7 (in thecase of an object to be processed being Al);

[0044]FIG. 10 is a table showing the result of test example 7 (in thecase of an object to be processed being W);

[0045]FIG. 11 is a table showing the result of test example 8 (in thecase of an object to be processed being Cu);

[0046]FIG. 12 is a table showing the result of test example 7 (in thecase of an object to be processed being Al);

[0047]FIG. 13 is a table showing the result of test example 7 (in thecase of an object to be processed being W);

[0048]FIG. 14 is a table showing the result of test example 10;

[0049]FIG. 15 is a table showing the result of test example 11 (in thecase of an object to be processed being Cu);

[0050]FIG. 16 is a table showing the result of test example 11 (in thecase of an object to be processed being Al);

[0051]FIG. 17 is a table showing the result of test example 12 (in thecase of an object to be processed being Cu); and

[0052]FIG. 18 is a table showing the result of test example 12 (in thecase of an object to be processed being Al).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] FIGS. 2(A) through 2(I) are diagrams illustrating a process offabricating a semiconductor device having a multi-layer wiring structureaccording to the present invention.

[0054] As referring to FIG. 2(A), an active region 11-A is formed on afield oxide film 11-1 on a Si substrate 11, and a gate electrode 12 isformed on the substrate 11 via a gate insulating film in the activeregion. Furthermore, diffusing regions 11-2 and 11-3 are formed at bothsides of the gate electrode 12 in the substrate 11, and moreover, achannel region 11-4 is formed just below the gate electrode 12. The gateelectrode 12 supports sidewall oxide films 12-1 and 12-2 on the surfacesof the sidewalls thereof. On the substrate 11, the first interlayerinsulation layer 13 is formed by a CVD (Chemical Vapor Deposition)method so as to cover the gate electrode 12.

[0055] As referring to FIG. 2(B), a Si₃N₄ film 14 as an etching stopperis formed on the first interlayer insulation layer 13 by the CVD method.A resist 15 is formed on the Si₃N₄ film 14. A fine pattern for a contacthole 16 is formed on the resist 15 by a photolithographic process.

[0056] As referring to FIG. 2(C), the Si₃N₄ film 14 is etched using theresist 15 as a mask so as to form the pattern for the contact hole 16-1and the resist 15 is eliminated.

[0057] As referring to FIG. 2(D), for example, an organic thermosettingresin is applied and heated so as to form the second interlayerinsulation layer 17 including an organic insulation layer. A SiO₂ film18 is formed on the second interlayer insulation layer 17 by p-TEOS.Furthermore, a resist 19 is formed on the SiO₂ film 18 and a pattern fora wiring slot 20 is formed on the resist 19 and used as an etching mask.

[0058] As referring to FIG. 2(E), the SiO₂ film 18 and the secondinterlayer insulation layer 17 are etched so as to form the wiring slot20-1. In this etching, the Si₃N₄ film 14 becomes a stopper.

[0059] As referring to FIG. 2(F), the first interlayer insulation layer13 is etched with the Si₃N₄ film 14 as a mask so as to form a contacthole 16-2 and the resist 19 is eliminated.

[0060] As referring to FIG. 2(G), a dual damascene structure thatincludes the wiring slot 20-1 and the contact hole 16-2 is formed.

[0061] As referring to FIG. 2(H), for suppressing the diffusion of Cu asthe wiring material to the first and second interlayer insulation layers13 and 17, a TiN film 21 is formed on the inner walls of the wiring slot20-1 and the contact hole 16-2, etc. Furthermore, a Cu film 22 isdeposited by an electrolytic plating method or the CVD method.

[0062] As referring to FIG. 2(I), the Cu film 22 is polished by the CMPmethod using an abrasive in which the abrasive grains include MnO,Mn₂O₃, or Mn₃O₄ and the additive is nitric acid HNO₃, until the SiO₂film 18 is exposed. In such an abrasive, the polishing speed for the Cufilm 22 is equal to or more than the polishing speed for the SiO₂ film18 as described in detail in the following test examples. The Cu film 22is polished selectively and the SiO₂ film 18 functions as a polishingstopper. Finally, the Cu film 22 is polished until the upper surface ofthe Cu film 22 has a co-plane with the upper surface of the SiO₂ film 18and a Cu dual damascene wiring is formed in which the wiring slot 20-1and the contact hole 16-2 are filled with the Cu film 22.

[0063] Subsequently, in order to eliminate the abrasive grains such asMn₂O₃, etc., remaining on the surface, washing is made using a brushscrubber and an aqueous solution of an organic acid, and further washingis accomplished using a dilute HF solution.

[0064] Embodiments according to the present invention will be describedin detail below.

[0065] Test examples 1 and 2 of the embodiments according to the presentinvention described below are examples in regard to abrasives in whichthe abrasive grains include MnO, Mn₂O₃, or Mn₃O₄ and the additive isnitric acid HNO₃.

[0066] {Test Example 1}

[0067] In the subject test example, an abrasive was prepared by mixingabrasive grains including MnO, Mn₂O₃, or Mn₃O₄ with an average graindiameter of 0.2 μm, an additive, and a solvent. The composition of theabrasive was adjusted by using nitric acid HNO₃ as the additive and H₂O₂as the solvent such that the proportion of the abrasive grains in theabrasive was 10 wt % and pH of the abrasive was 1.5 (samples 11 through13). An abrasive in which the abrasive grains were MnO₂ and the othershave compositions similar to samples 11 through 13 was a comparison(sample 14).

[0068] Also, the object to be processed was provided by forming a SiO₂layer with the thickness of 1 μm on a wafer by p-TEOS, subsequentlyforming a hole with the diameter of 0.35 μm and the height of 0.5 μm,forming a TiN layer with the thickness of 5 nm by a sputtering method,and further forming a W layer with the thickness of 500 nm by the CVDmethod.

[0069] For the polishing, a polishing apparatus as shown in FIG. 3 wasemployed. FIG. 3(A) is a schematic diagram showing the structure of apolishing apparatus and FIG. 3(B) is a schematic diagram showing thestructure of a polishing apparatus to which a dress jig is attached.

[0070] As referring to FIGS. 3(A) and (B), the polishing conditionswere: IC1400 made by Rodel as the polishing cloth 101, the pressure of3.4×10⁴ Pa, the number of revolutions of the upper surface plate 102 of50 rpm, and the number of revolution of the lower surface plate 103 of40 rpm. Also, the abrasive was supplied from an abrasive-supplyingapparatus 104, and the flow rate of the abrasive was 0.1 L/min.Additionally, an object to be processed 105, of which the surface to beprocessed was directed downward, was attached to the upper surface plate102.

[0071] As referring to FIG. 3(B), a fixed grindstone 121 in whichdiamond abrasive grains were fixed with resin, etc., was attached to adress jig 120. In the present test example, dressing was performed incombination with the polishing by the polishing apparatus 110 shown inFIG. 3(B).

[0072] For the test, the W layer and the TiN layer on the wafer asobjects to be processed were polished for each sample of the abrasive,and over-polishing was further performed for 2 minutes. 1000 wafers werepolished continuously. Subsequently, the surface of the processed objectwas examined by a surface inspection apparatus in regard to the presenceor absence of damage. TABLE 1 Rate of Number of occurrence Abrasivewafers with of damage Abrasive grain damage (%) Sample 11 MnO 2 0.2Sample 12 Mn₂O₃ 1 0.1 Sample 13 Mn₃O₄ 2 0.2 Sample 14 MnO₂ 65 6.5(Comparison)

[0073] Table 1 shows the result of test example 1. The rate ofoccurrence of damage caused by the dressing with abrasives of which theabrasive grains were MnO, Mn₂O₃, or Mn₃O₄ was significantly lower thanwith the abrasive in which the abrasive grains were MnO₂ as acomparison. It is considered that for the abrasive in which the abrasivegrains were MnO₂, resin such as epoxy resin for fixing diamond abrasivegrains of the dress jig are dissolved with MnO₂, and the diamondabrasive grains remain on the polishing cloth so as to damage the wafer.In the cases of MnO, Mn₂O₃, and Mn₃O₄, polishing can be made withoutgenerating such a problem. This knowledge was first elucidated by aseries of studies by the inventors of the present invention.

[0074] {Test Example 2}

[0075] In the subject test example, an abrasive was prepared by mixingabrasive grains including MnO, Mn₂O₃, or Mn₃O₄ that have the averagegrain diameter of 0.2 μm, an additive, and a solvent. Nitric acid HNO₃was used as the additive, H₂O₂ was used as the solvent, the proportionof the abrasive grains in the abrasive was adjusted to 10 wt %, and pHof the abrasive was adjusted to 3.0 (samples 21 through 23). An abrasiveof which abrasive grains were MnO₂ and other conditions were similar tothose of samples 21 through 23 was used as a comparison (sample 24).

[0076] Also, an object to be processed was prepared such that a SiO₂layer with the thickness of 1 μm was formed on a wafer (work 2A) andanother object to be processed was also prepared such that after a SiO₂layer with the thickness of 1 μm was formed on a wafer, a TiN layer withthe thickness of 5 nm was formed on the SiO₂ layer by the sputteringmethod and a W layer with the thickness of 500 nm was further formed onthe TiN layer by the CVD method (work 2B).

[0077] The polishing condition for the subject test example was the sameas the condition for the test example 1.

[0078] For the test, the respective abrasives were used and the work 2Aand the work 2B were polished for certain periods, respectively. Then,the amount of material removed by the polishing was determined and theratio V_(W)/V_(siO2) of the polishing speed for the W layer to thepolishing speed for the SiO₂ layer, the so-called selection ratio, wasobtained. Herein, V_(W) is the polishing speed for the W layer andV_(SiO) ₂ is the polishing speed for the SiO₂ layer. TABLE 2 AbrasivePolishing Speed Abrasive Grain Ratio V_(W)/V_(SiO2) Sample 21 MnO 30Sample 22 Mn₂O₃ 10 Sample 23 Mn₃O₄ 35 Sample 24 MnO₂ 40 (Comparison)

[0079] Table 2 shows the result of test example 2. When a metal layer ispolished, it is preferable that the ratio V_(W)/V_(SiO) ₂ of thepolishing speeds be greater. From Table 2, the selection ratios for theabrasives containing the abrasive grains of MnO, MnO₂, or Mn₃O₄ and NO₃⁻ were equal to or more than 10. When a metal layer on an oxide film waspolished, the oxide film acted as a polishing stopper.

[0080] According to the test examples 1 and 2, the selection ratio forthe abrasive containing the abrasive grains of MnO₂ and NO₃ ⁻ as acomparison are sufficient, but the rate of occurrence of damage is highso as to be a real problem. However, for the polishing with theabrasives containing the abrasive grains of MnO, Mn₂O₃, or Mn₃O₄ and NO₃⁻ according to the present embodiment, there is very little damage bydressing and the selection ratio is equal to or more than 10. Also, whena metal layer on an oxide film is polished, the oxide film can act as apolishing stopper.

[0081] Test example 3 of the embodiment according to the presentinvention mentioned below is an example of an abrasive having abrasivegrains including MnO or MnO₂ and an organic acid as an additive.

[0082] {Test Example 3}

[0083] In the subject test example, an abrasive was prepared by mixingabrasive grains including MnO, MnO₂, Mn₂O₃, or Mn₃O₄ with an averagegrain diameter of 0.2 μm and a solvent. H₂O₂ was used as the solvent andthe composition of the abrasive was adjusted such that the proportion ofthe abrasive grains in the abrasive was 10 wt % (samples 31 through 34).

[0084] Then, the test was performed on the two conditions of providingand not providing a solution containing, for example, 5 wt % of anorganic acid. The solution was provided to a polishing apparatus througha route different from the route for the abrasive. Herein, the organicacid was gluconic acid (C₆H₁₂O₇) , ortho-methyl benzoic acid(CH₃-C₆H₄—COOH), citric acid (C₆H₈O₇), malonic acid (CH₂(COOH)₂) oracetic acid (CH₃COOH).

[0085] Also, one object to be processed was such that a SiO₂ layer withthe thickness of 1 μm was formed on a wafer (work 3A) and another objectto be processes was such that after a SiO₂ layer with the thickness of 1μm was formed on a wafer, a TiN layer with the thickness of 5 nm wasformed on the SiO₂ layer by the sputtering method and a Cu layer, an Allayer, or a W layer with the thickness of 500 nm was further formed onthe TiN layer by the CVD method (works 3B through 3D).

[0086] The polishing condition for the subject test example was the sameas the condition for the test example 1.

[0087] For the test, respective abrasives were used and the works 3Athrough 3D as the objects to be processed were polished for certainperiods on the conditions of providing and not providing the solutioncontaining the organic acid. Then, the amounts of material removed bypolishing were determined for works 3A through 3D on the respectiveconditions and the polishing speeds for the Cu layer, the Al layer, theW layer and the SiO₂ layer were obtained.

[0088] The polishing speed for the SiO₂ layer was lowered as the organicacid was supplied. Also, the Cu layer, the Al layer, and the W layerwere not corroded by the organic acid. Accordingly, when a metal layeron an oxide film is polished, the metal layer only can be polished andthe oxide film can act as a polishing stopper.

[0089] Additionally, in the subject test example, the solutioncontaining the organic acid was provided to a polishing apparatusthrough a route different from the route for the abrasive. However, thesolution containing the organic acid may be mixed with the abrasive justbefore the mixture is provided to the polishing apparatus.

[0090] Test example 4 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished by using H₂O₂ solution.

[0091] {Test Example 4}

[0092] In the subject test example, an abrasive was prepared by mixingabrasive grains including MnO, MnO₂, Mn₂O₃, or Mn₃O₄ with an averagegrain diameter of 0.2 μm and a solvent. H₂O₂ was used as the solvent andthe composition of the abrasive was adjusted such that the proportion ofthe abrasive grains in the abrasive was 10 wt % (samples 41 through 44).

[0093] Also, one object to be processed was formed such that after anoxide film with the thickness of 20 nm was formed by means of thermaloxidation of a Si wafer, a TiN layer with the thickness of 5 nm wasformed on the Si wafer by the sputtering method and an Ir layer with thethickness of 100 nm was further formed on the TiN layer by the CVDmethod (work 4A). Another object to be processed was formed such thatafter an oxide film with the thickness of 20 nm was formed by means ofthermal oxidation of a Si wafer, a Ta layer with the thickness of 50 nmwas formed on the Si wafer by a sputtering method (work 4B). Thelamination structure of works 4A and 4B were as follows.

[0094] Work 4A: Ir layer (100 nm)/TiN layer (5 nm)/SiO₂ layer (20 nm)/Sisubstrate

[0095] Work 4B: Ta layer (50 nm)/SiO₂ layer (20 nm)/Si substrate

[0096] The polishing conditions were two conditions of providing and notproviding an aqueous solution containing 5 wt % of H₂O₂. Herein, theH₂O₂ aqueous solution was provided to a polishing apparatus by a routedifferent from the route for the abrasive. Other polishing conditionswere the same as the conditions for the test example 1.

[0097] For the test, the respective abrasives were used and the works 4Aand 4B as the objects to be processed were polished for certain periodson the conditions of providing and not providing the H₂O₂ aqueoussolution. Then, on each condition, the amount of material removed bypolishing was determined for works 4A and 4B and the ratioV_(H2O2)/V_(O) of the polishing speeds for the cases of providing andnot providing the H₂O₂ aqueous solution was obtained. Herein, V_(H2O2)is the polishing speed for the case of providing the H₂O₂ aqueoussolution and V_(O) is the polishing speed for the case of not providingthe H₂O₂ aqueous solution. TABLE 3 Abrasive Object to be Abrasive grainprocessed V_(H2O2)/V_(O) Sample 41 MnO Work 4A (Ir) 960 Work 4B (Ta) 240Sample 42 MnO₂ Work 4A (Ir) 970 Work 4B (Ta) 260 Sample 43 Mn₂O₃ Work 4A(Ir) 980 Work 4B (Ta) 250 Sample 44 Mn₃O₄ Work 4A (Ir) 1000 Work 4B (Ta)240

[0098] Table 3 shows the result of the subject test example. Asreferring to Table 3, when the Ir layer or the Ta layer as the object tobe processed was polished using the abrasive with the abrasive grains ofMnO, MnO₂, Mn₂O₃, or Mn₃O₄, the polishing speed for the case ofproviding the H₂O₂ aqueous solution was increased, compared to the caseof non-providing the H₂O₂ aqueous solution. Then, although there has notyet been provided an abrasive capable of polishing an Ir layer and a Talayer being chemically stable, the Ir layer and the Ta layer can bepolished efficiently according to the subject test example.

[0099] Additionally, in the subject test example, the H₂O₂ aqueoussolution was provided to a polishing apparatus by a route different fromthe route for the abrasive. However, the H₂O₂ solution may be mixed withthe abrasive just before the mixture is provided to the polishingapparatus.

[0100] Test example 5 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished with an abrasive containing abrasivegrains including MnO, MnO₂, Mn₂O₃, or Mn₃O₄ and an additive provided byroutes different from each other.

[0101] {Test Example 5}

[0102] In the subject test example, an abrasive was prepared by mixingabrasive grains including MnO, MnO₂, Mn₂O₃, or Mn₃O₄ with an averagegrain diameter of 0.2 μm and a solvent (Samples 51 through 54). H₂O₂ wasused as the solvent and the composition of the abrasive was adjustedsuch that the proportion of the abrasive grains in the abrasive was 10wt %.

[0103] In respect to the polishing condition, a supplied solutioncontaining an additive shown in each of the following polishingconditions 1 through 9 was provided to a polishing apparatus at a rateof 0.1 L/min, and other conditions were similar to those of the testexample 1.

[0104] Also, for the object to be processed, a 200 nm SiO₂ layer wasformed on a Si substrate, and one of the following various conductivefilms with the thickness of 50 nm was formed on the substrate by thesputtering method.

[0105] In respect to the test, the objects to be processed (works 51through 5J) were polished with the respective abrasives (Samples 51through 54) for 3 minutes on the polishing conditions. Also, whether amaterial of the object to be processed remained on the top surface ornot was determined. Then, the case of not remaining, where the materialof the top surface was entirely polished, was judged to be polishable(0) and the case of remaining was judged to be not-polishable (X).

[0106] (Abrasives)

[0107] Sample 51: abrasive grains of MnO₂, 10 wt % of solid content, noadditive

[0108] Sample 52: abrasive grains of Mn₂O₃, 10 wt % of solid content, noadditive

[0109] Sample 53: abrasive grains of Mn₃O₄, 10 wt % of solid content, noadditive

[0110] Sample 54: abrasive grains of MnO, 10 wt % of solid content, noadditive

[0111] (Polishing Conditions)

[0112] Polishing condition 51 (comparison): supplied solution of onlyH₂O

[0113] Polishing condition 52: supplied solution of HNO₃ aqueoussolution at pH 2

[0114] Polishing condition 53: supplied solution of 10 wt % of Potassiumphthalate aqueous solution

[0115] Polishing condition 54: supplied solution of 10 wt % of gluconicacid (C₆H₁₂O₇) aqueous solution

[0116] Polishing condition 55: supplied solution of 5 wt % ofortho-methylbenzoic acid (CH₃-C₆H₄—COOH) aqueous solution

[0117] Polishing condition 56: supplied solution of 10 wt % of citricacid (C₆H₈O₇) aqueous solution

[0118] Polishing condition 57: supplied solution of 10 wt % of malonicacid (CH₂(COOH)₂) aqueous solution

[0119] Polishing condition 58: supplied solution of acetic acid(CH₃COOH) aqueous solution at pH 3

[0120] Polishing condition 59: supplied solution of 10 vol% of H₂O₂aqueous solution.

[0121] The film structure of the objects to be processed will be shownbelow. Herein, the Si substrate and the SiO₂ (200 nm) formed thereon areomitted.

[0122] Work 51: Ti (50 nm)

[0123] Work 52: TiN (50 nm)

[0124] Work 53: Cr (50 nm)/TiN (50 nm)

[0125] Work 54: Co (50 nm)/TiN (50 nm)

[0126] Work 55: Fe (50 nm)/TiN (50 nm)

[0127] Work 56: Ni (50 nm)/TiN (50 nm)

[0128] Work 57: Nb (50 nm)/TiN (50 nm)

[0129] Work 58: Mo (50 nm)/TiN (50 nm)

[0130] Work 59: MoO (50 nm)/TiN (50 nm)

[0131] Work 5A: Mo₂N (50 nm)/TiN (50 nm)

[0132] Work 5B: Ru (50 nm)/TiN (50 nm)

[0133] Work 5C: RuO (50 nm)/TiN (50 nm)

[0134] Work 5D: Pd (50 nm)/TiN (50 nm)

[0135] Work 5E: Hf (50 nm)/TIN (50 nm)

[0136] Work 5F: Ta (50 nm)/TiN (50 nm)

[0137] Work 5G: TaN (50 nm)/TiN (50 nm)

[0138] Work 5H: WN (50 nm)/TiN (50 nm)

[0139] Work 5I: Ir (50 nm)/TiN (50 nm)

[0140] Work 5J: IrO (50 nm)/TiN (50 nm).

[0141]FIG. 4 is a table showing the result of the subject test example.As referring to FIG. 4, for the kinds of polishable metals andintermetallic compounds thereof for all samples for the abrasives andthe additive of HNO₃, the organic acids such as gluconic acid, etc., andH₂O₂ in the polishing conditions 52 through 59 were more than in thepolishing condition 51 as a comparison, where only H₂O₂ was supplied.Particularly, when the HNO₃ solution was provided, metals except Ni, Pd,Hf, Ta, and Ir and intermetallic compounds thereof were polishable.Furthermore, in the case of the polishing conditions 9 using H₂O₂solution, all metals and intermetallic compounds thereof in the subjecttest example were polishable. Therefore, many kinds of metals andintermetallic compounds thereof used in a semiconductor device can bepolished with one kind of abrasive provided by supplying an additiveaccording to the subject test example to the abrasive in which abrasivegrains of any of Mno, MnO₂, Mn₂O₃, and Mn₃O₄ are mixed with a solventthereof. Accordingly, since the kinds of abrasive grain components usedcan be controlled to generate a minimum of polishing waste, the waste iseasily treated, recovered, and recycled.

[0142] Also, since the additive is provided by a route different fromthe route for the abrasive, a dispersing agent for improving thedispersion property of the abrasive grains may be added to the abrasive,independent of the composition of the additive.

[0143] Test example 6 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished with a solid abrasive prepared by coolingand solidifying abrasive grains including MnO, MnO₂, Mn₂O₃, or Mn₃O₄ anda solvent thereof.

[0144] {Test Example 6}

[0145] In the subject test example, abrasive grains including MnO₂,Mn₂O₃, Mn₃O₄, or MnO with an average grain diameter of 0.2 μm and H₂O₂as a solvent thereof were used. The abrasive grains were mixed with thesolvent, and the mixture was cooled and solidified so as to form a solidabrasive. The composition of the abrasive was adjusted such that theproportion of the abrasive grains in the abrasive was 50 wt % (Samples61 through 64). Additionally, the solid abrasive was also cooled withliquid nitrogen in order to keep the solid abrasive cold.

[0146] In addition, an abrasive of which the abrasive grains were silicawith an average grain diameter of 0.2 μm was prepared and then theprepared abrasive was solidified similarly, so as to provide acomparison (Sample 65). Furthermore, unsolidified abrasives wereprepared as comparisons (Samples 66 through 6A).

[0147] Also, an object to be processed was formed such that a SiO₂ layerwith the thickness of 1 μm was formed on a wafer by p-TEOS (work 61).Another object to be processed was formed such that a SiO₂ layer withthe thickness of 0.2 μm was formed on a wafer by p-TEOS and apolysilicon layer with the thickness of 1 μm was formed on the SiO₂layer by the CVD method.

[0148] The solid abrasive was provided to the polishing apparatus shownin FIG. 5. FIG. 5 is a schematic diagram of the polishing apparatus usedin the subject test example. The polishing apparatus 200 includes anupper surface plate 202 and a lower surface plate 203. An object to beprocessed 205 was fixed on the lower surface plate 203 and the object tobe processed 205 was rotated with a certain number of revolutions. Theside of the upper surface plate 202 facing the object to be processed isin the form of a cylinder, of which the inside is a cavity part 202-1 asa cavity. The cavity part 202-1 holds a solid abrasive, in which ahold-back agent such as ice is mixed, and is cooled with liquidnitrogen, etc. The cavity part 202-1 is connected with a pressurized-airsupplying route 204 provided on a driving shaft of the upper surfaceplate 202. The solid abrasive is also pressurized so as to pass throughthe route 204 from the outside of the upper surface plate 202. Due tothe rotation of the upper surface plate 202, the solid abrasive 210 heldon the cavity part 202-1 gradually melts in a region contacting thesurface of the object to be processed 205 and the melted abrasivepolishes the object to be processed 205.

[0149] H₂O was supplied through an additive supplying route 206 on theconditions of 9.8×10³ Pa as the pressure, 1.47×10⁴ Pa as the pressure ofthe pressurized air in the pressurized air supplying route 204, 2000 rpmas the number of revolutions of the upper surface plate 202, and 70 rpmas the number of revolutions of the lower surface plate 203 (polishingcondition 61). Additionally, since air leaks from a gap between thesolid abrasive and the cavity part 202-1, the pressure of thepressurized air applied on the surface of the object to be processed 205is reduced.

[0150] For abrasive samples 66 through 6A, the polishing apparatus 100and the polishing conditions similar to those of the test example, inwhich the abrasive is free abrasive grains, were employed (polishingcondition 62).

[0151] (Abrasives)

[0152] Sample 61: the solid abrasive, the abrasive grains of MnO₂ (20 wt%), the hold-back agent of ice, none of the additive

[0153] Sample 62: the solid abrasive, the abrasive grains of Mn₂O₃ (20wt %) , the hold-back agent of ice, none of the additive

[0154] Sample 63: the solid abrasive, the abrasive grains of Mn₃O₄ (20wt %) , the hold-back agent of ice, none of the additive

[0155] Sample 64: the solid abrasive, the abrasive grains of MnO (20 wt%), the hold-back agent of ice, none of the additive

[0156] Sample 65 (Comparison): the solid abrasive, the abrasive grainsof SiO₂ (20 wt %), none of the additive

[0157] Sample 66 (Comparison): the liquid abrasive, the abrasive grainsof MnO₂, 10 wt % of the solid content, none of the additive

[0158] Sample 67 (Comparison): the liquid abrasive, the abrasive grainsof Mn₂O₃, 10 wt % of the solid content, none of the additive

[0159] Sample 68 (Comparison): the liquid abrasive, the abrasive grainsof Mn₃O₄, 10 wt % of the solid content, none of the additive

[0160] Sample 69 (Comparison): the liquid abrasive, the abrasive grainsof MnO, 10 wt % of the solid content, none of the additive

[0161] Sample 6A (Comparison): the liquid abrasive, the abrasive grainsof SiO₂, 10 wt % of the solid content, none of the additive

[0162] (Objects to be Processed)

[0163] Work 61: SiO₂ (1 μm)/wafer

[0164] Work 62: Polysilicon (1 μm) /SiO₂ (0.2 μm)/wafer

[0165]FIG. 6 is a table showing the result of the subject test example.As referring to FIG. 6, the polishing speed of the abrasive containingsilica (SiO₂) of sample 65 as a comparison is greatly lowered, comparedto the liquid abrasive containing silica of sample 6A as a comparison.However, the solid abrasive of which the abrasive grains are MnO₂,Mn₂O₃, Mn₃O₄, or MnO according to the test example of the presentinvention has a polishing speed similar to that of the liquid abrasiveas a comparison (samples 66 through 69). Also, the mass of the solidabrasive grains necessary for polishing the object to be processed by 1μm according to the test example of the present invention is 10% of themass of the liquid abrasive grains necessary for polishing the object tobe processed by 1 μm. Therefore, the solid abrasive according to thetest example of the present invention can significantly reduce theamount of waste produced in the abrasive process.

[0166] Test example 7 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished with a solid abrasive provided by coolingand solidifying abrasive grains including MnO, MnO₂, Mn₂O₃, and Mn₃O₄, asolvent, and an additive.

[0167] {Test Example 7}

[0168] In the subject test example, the abrasive grains including MnO,MnO₂, Mn₂O₃, or Mn₃O₄ with the average grain diameter of 0.2 μm and H₂Oas the solvent thereof were used. The abrasive grains, the solvent andthe additive were mixed so as to form the abrasive and the mixture wascooled and solidified. As the additive, each of HNO₃, potassiumphthalate, and ortho-methylbenzoic acid was used as shown below. Thecomposition of the abrasive was adjusted such that the proportion of theabrasive grains in the abrasive was 20 wt % (Samples 71 through 7G).Also, in order to keep the solid abrasive cold, the solid abrasive wasfurther cooled with liquid nitrogen.

[0169] As a comparison, an abrasive was prepared by using the abrasivegrains, the solvent, and the additive similar to those of the samples 71through 7G without cooling and solidifying. Herein, the composition ofthe abrasive was adjusted such that the proportion of the abrasivegrains in the abrasive was 10 wt % (samples 7H through 7W).

[0170] As the object to be processed, after a SiO₂ layer with thethickness of 200 nm was formed on a Si substrate by p-TEOS, a Ta layerwith the thickness of 5 nm was formed on the SiO₂ layer by thesputtering method, and a Cu layer with the thickness of 800 nm wasfurther formed on the Ta layer by the sputtering method (work 71). Also,after a SiO₂ layer with the thickness of 200 nm was formed on a Sisubstrate by p-TEOS, a TiN layer with the thickness of 50 nm was formedon the SiO₂ layer by the sputtering method, and an Al layer with thethickness of 800 nm was further formed on the TiN layer by thesputtering method (work 72). Furthermore, after a SiO₂ layer with thethickness of 200 nm was formed on a Si substrate by p-TEOS, a TiN layerwith the thickness of 50 nm was formed on the SiO₂ layer by thesputtering method, and a W layer with the thickness of 800 nm wasfurther formed on the TiN layer by the CVD method (work 73). Moreover,as a comparison, a SiO₂ layer with the thickness of 1 μm was formed on aSi substrate by p-TEOS (work 74).

[0171] The polishing condition of the solid abrasives (sample 71 through7G) was similar to the polishing condition 61 of the test example 6(polishing condition 71). Also, the abrasive condition of the abrasivesincluding free abrasive grains (samples 7H thorough 7W) was similar tothe abrasive condition 62 of the test example 6 (abrasive condition 72).

[0172]FIG. 7 is a table showing the conditions of the samples of theabrasive. Also, the film structure of the objects to be processed willbe shown below. Herein, the Si substrate is omitted.

[0173] Work 71: Cu (800 nm)/Ta (5 nm)/SiO₂ (200 nm)

[0174] Work 72: Al (800 nm)/TiN (50 nm)/SiO₂ (200 nm)

[0175] Work 73: W (800 nm)/TiN (50 nm)/SiO₂ (200 nm)

[0176] Work 74: SiO₂ (1 μm)

[0177]FIGS. 8 through 10 are diagrams showing the result of the subjecttest example. FIG. 8 shows the case where the top surface layer of theobject to be processed was made from Cu (work 71). FIG. 9 shows the casewhere the top surface layer of the object to be processed was made fromAl (work 72). FIG. 10 shows the case where the top surface layer of theobject to be processed was made from W (work 73). In respectivediagrams, the case where the top surface layer as an insulation layerwas made from SiO₂ (work 74) is also shown for comparison.

[0178] According to FIGS. 8 through 10, the polishing speed for SiO₂ canbe reduced by adding HNO₃, potassium phthalate, or ortho-methylbenzoicacid as the additive to the abrasive, compared to the case of none ofthe additive.

[0179] On the other hand, the polishing speeds for Cu, Al, and W weresimilarly increased by the addition of HNO₃, potassium phthalate,gluconic acid, ortho-methylbenzoic acid, citric acid, malonic acid, oracetic acid. Particularly, the polishing speeds in the cases of Cu andAl were significantly increased so as to improve the selectivity of thepolishing.

[0180] Therefore, the selectivity for polishing the metal layers andSiO₂ layer can be improved by the solid abrasive prepared by cooling andsolidifying the abrasive which is formed by mixing the abrasive grainsincluding each of MnO₂, Mn₂O₃, Mn₃O₄, and MnO, with H₂O as the solvent,and the additive of HNO₃, potassium phthalate, gluconic acid,ortho-methylbenzoic acid, citric acid, malonic acid, or acetic acid.Thus the solid abrasive can be used for metal-embedding polishing in aprocess of fabricating a semiconductor device. Additionally, the loadingof the abrasive grains can be reduced.

[0181] Test example 8 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished by supplying a solid abrasive obtained bysolidifying the abrasive in which an additive is not added, and anadditive such as HNO₃, etc., using an additive feeder.

[0182] {Test Example 8}

[0183] The abrasive grains including MnO₂, Mn₂O₃, Mn₃O₄, or MnO with anaverage grain diameter of 0.2 μm and H₂O as the solvent were used andmixed without addition of an additive, so as to form the abrasive, whichwas subsequently cooled and solidified. The composition of the abrasivewas adjusted such that the proportion of the abrasive grains in theabrasive was 20 wt % (Samples 81 through 84). Also, in order to keep thesolid abrasive cold, the solid abrasive was further cooled with liquidnitrogen.

[0184] The objects to be processed similar to those of works 71 through74 of the test example 7 were used (works 81 through 84).

[0185] The abrasive condition was similar to the polishing condition 61of the test example 6 and the additive shown below was supplied on asurface to be polished by the additive feeder shown in FIG. 5 (polishingconditions 81 through 84).

[0186] (Abrasives)

[0187] Sample 81: Abrasive grains of MnO₂ (20 wt %), a hold-back agent,ice, none of additive

[0188] Sample 82: Abrasive grains of Mn₂O₃ (20 wt %), a hold-back agent,ice, none of additive

[0189] Sample 83: Abrasive grains of Mn₃O₄ (20 wt %), a hold-back agent,ice, none of additive

[0190] Sample 84: Abrasive grains of MnO (20 wt %), a hold-back agent,ice, none of additive

[0191] (Polishing Conditions)

[0192] Polishing condition 81 (comparison): supplied solution of onlyH₂O₂

[0193] Polishing condition 82: supplied solution of HNO₃ aqueoussolution at pH 2

[0194] Polishing condition 83: supplied solution of 10 wt % of potassiumphthalate aqueous solution

[0195] Polishing condition 84: supplied solution of 5 wt % ofortho-methylbenzoic acid aqueous solution

[0196]FIGS. 11 through 13 are tables showing the results of the subjecttest example. FIG. 11 shows the case where the top surface layer of theobject to be processed was made from Cu (work 81). FIG. 12 shows thecase where the top surface layer of the object to be processed was madefrom Al (work 82). FIG. 13 shows the case where the top surface layer ofthe object to be processed was made from W (work 83). In respectivediagrams, the case where the top surface layer as an insulation layerwas made from SiO₂ (Work 74) is also shown for comparison.

[0197] As referring to FIGS. 11 through 13, the polishing speed for SiO₂can be reduced and the polishing speeds for Cu, Al, and W werecomparable or increased in the case of supplying HNO₃, potassiumphthalate, or ortho-methylbenzoic acid as the additive, compared to thecase of supplying only H₂O as the additive to the solid abrasive in thepolishing apparatus, so as to improve the selectivity for the polishing.In particular, the polishing speeds for Cu and Al were significantlyincreased, so as to improve the selectivity for the polishingsignificantly. Furthermore, when the object to be processed was madefrom Cu or Al, the abrasive grains necessary for polishing by 1 μm weresignificantly reduced by supplying such additive, compared to the caseof supplying only H₂O. Accordingly, the loading of the abrasive grainscan be significantly reduced by supplying the additive to the solidabrasive.

[0198] Test example 9 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished with a solid abrasive obtained bysolidifying an abrasive without an additive or a solid abrasive obtainedby solidifying an abrasive in which H₂O₂ is added as an additive.

[0199] {Test Example 9}

[0200] The solid abrasives were formed for abrasive grains of MnO₂,Mn₂O₃, Mn₃O₄, or MnO, respectively, similar to test example 8 (samples91 through 94). Also, in order to keep the solid abrasive cold, thesolid abrasives were further cooled with liquid nitrogen.

[0201] The objects to be processed similar to those of works 4A and 4Bof test example 4 were used (works 91 and 92). The top surface layers ofthem were an Ir layer and a Ta layer, respectively.

[0202] The polishing condition was similar to polishing condition 61 oftest example 6, and H₂O₂ aqueous solution (concentration of 3 wt %) wassupplied on a surface to be polished from the additive feeder 206 inFIG. 5. On the other hand, the case of supplying only H₂O was acomparison.

[0203] (Abrasives)

[0204] Sample 81: abrasive grains of MnO₂ (20 wt %), a hold-back agentof ice, none of additive

[0205] Sample 82: abrasive grains of Mn₂O₃ (20 wt %), a hold-back agentof ice, none of additive

[0206] Sample 83: abrasive grains of Mn₃O₄ (20 wt %), a hold-back agentof ice, none of additive

[0207] Sample 84: abrasive grains of MnO (20 wt %), a hold-back agent ofice, none of additive TABLE 4 Abrasive Object to be Abrasive grainprocessed V_(H2O2)/V_(O) 91 MnO₂ Ir 920 91 Ta 260 92 Mn₂O₃ Ir 940 92 Ta240 93 Mn₃O₄ Ir 960 93 Ta 230 94 MnO Ir 950 94 Ta 240

[0208] Table 4 shows the result of the subject test example. Accordingto Table 4, the polishing speeds for the Ir layer and the Ta layer weresignificantly increased in the case of supplying H₂O₂ solution, comparedto the case of supplying only H₂O to the solid abrasive.

[0209] Accordingly, when the material for wiring of a semiconductordevice is Ir or Ta, although there has been provided no abrasive usefulfor polishing because of the chemical stability, an Ir layer and a Talayer can be polished efficiently according to the subject test example.

[0210] Test example 10 of the embodiment according to the presentinvention mentioned below is an example of a method of fabricating asemiconductor device polished with a solid abrasive obtained bysolidifying one abrasive in which an additive is not included or anotherabrasive in which an additive of HNO₃, potassium phthalate, an organicacid, or H₂O₂ is included.

[0211] {Test Example 10}

[0212] Similar to test example 8, the solid abrasive including abrasivegrains of MnO₂, Mn₂O₃, Mn₃O₄, or MnO was formed (samples 101 through104). Also, in order to keep the solid abrasive cold, the solid abrasivewas further cooled with liquid nitrogen.

[0213] The objects to be processed were similar to works 51 through 5Jof test example 5 (works 101 through 10J).

[0214] In respect to the polishing condition, a solution to be suppliedthat contains each of additives for the polishing conditions 101 through109 mentioned below was supplied to the polishing apparatus 200 at therate of 0.1 1/min by the additive feeder 206, and other conditions weresimilar to polishing condition 61 of test example 6.

[0215] (Abrasives)

[0216] Sample 101: abrasive grains of Mn₂O₃, 20 wt % of solid content, ahold-back agent of ice, none of additive

[0217] Sample 102: abrasive grains of Mn₂O₃, 20 wt % of solid content, ahold-back agent of ice, none of additive

[0218] Sample 103: abrasive grains of Mn₃O₄, 20 wt % of solid content, ahold-back agent of ice, none of additive

[0219] Sample 104: abrasive grains of MnO, 20 wt % of solid content, ahold-back agent of ice, none of additive

[0220] (Polishing Conditions)

[0221] Polishing condition 101: supplied solution of only H₂O

[0222] Polishing condition 102: supplied solution of HNO₃ aqueoussolution at pH 12

[0223] Polishing condition 103: supplied solution of 10 wt % ofpotassium phthalate aqueous solution

[0224] Polishing condition 104: supplied solution of 10 wt % of gluconicacid (C₆H₁₂O₇) aqueous solution

[0225] Polishing condition 105: supplied solution of 5 wt % ofortho-methylbenzoic acid (CH₃-C₆H₄—COOH) aqueous solution

[0226] Polishing condition 106: supplied solution of 10 wt % of citricacid (C₆H₈O₇) aqueous solution

[0227] Polishing condition 107: supplied solution of 10 wt % of malonicacid (CH₂(COOH)₂) aqueous solution

[0228] Polishing condition 108: supplied solution of acetic acid(CH₃COOH) aqueous solution at pH 3

[0229] Polishing condition 109: supplied solution of 10 vol% of H₂O₂aqueous solution

[0230] The film structure of the objects to be processed will be shownbelow. Herein, the Si substrate and the SiO₂ (200 nm) formed thereon areomitted.

[0231] Work 101: Ti (50 nm)

[0232] Work 102: TiN (50 nm)

[0233] Work 103: Cr (50 nm)/TiN (50 nm)

[0234] Work 104: Co (50 nm)/TiN (50 nm)

[0235] Work 105: Fe (50 nm)/TiN (50 nm)

[0236] Work 106: Ni (50 nm)/TiN (50 nm)

[0237] Work 107: Nb (50 nm)/TiN (50 nm)

[0238] Work 108: Mo (50 nm)/TiN (50 nm)

[0239] Work 109: MoO (50 nm)/TiN (50 nm)

[0240] Work 10A: MO₂N (50 nm)/TiN (50 nm)

[0241] Work 10B: Ru (50 nm)/TiN (50 nm)

[0242] Work 10C: RuO (50 nm)/TiN (50 nm)

[0243] Work 10D: Pd (50 nm)/TiN (50 nm)

[0244] Work 10E: Hf (50 nm)/TiN (50 nm)

[0245] Work 10F: Ta (50 nm)/TiN (50 nm)

[0246] Work 10G: TaN (50 nm)/TiN (50 nm)

[0247] Work 10H: WN (50 nm)/TiN (50 nm)

[0248] Work 10I: Ir (50 nm)/TiN (50 nm)

[0249] Work 10J: IrO (50 nm)/TiN (50 nm)

[0250]FIG. 14 is a table showing the result of the subject test example.According to FIG. 14, the kinds of polishable metals and intermetalliccompounds thereof for all the samples of the solid abrasives in thecases of HNO₃, an organic acid such as gluconic acid, etc. and H₂O₂ aremuch more than in the case of supplying only water as polishingcondition 101. In particular, when HNO₃ solution is supplied, metalsexcept Ni, Hf, and Ir and intermetallic compounds thereof can bepolished. Furthermore, in the case of using H₂O₂ solution as polishingcondition 9, all the metals and intermetallic compounds thereof in thesubject test example can be polished.

[0251] Accordingly, many kinds of metals, etc., used in a semiconductordevice can be polished with one kind of the solid abrasive obtained bymixing and solidifying the abrasive grains of MnO, MnO₂, Mn₂O₃, orMn₃O₄, the solvent, and the additive in the subject test example.Accordingly, in regard to the treatment of waste caused by polishing,since the kind of abrasive grain components used can be controlled to beminimum, the waste is easily treated, recovered and recycled.

[0252] Additionally, although the solid abrasive that contains noadditive was employed in the subject test example, equivalent effect isobtained even if the additive is included.

[0253] Furthermore, in regard to test examples 6 through 10, in thepolishing apparatus shown in FIG. 5, a polishing cloth, for example,IC1000 made by Rodel, may be applied on the upper surface plate 202, sothat the object to be processed 205 contacts the polishing cloth.

[0254] Test example 11 of the embodiment according to the presentinvention mentioned below is an example of washing for a semiconductordevice polished by using an abrasive containing abrasive grains ofmanganese oxide such as MnO₂, Mn₂O₃, Mn₃O₄, and MnO.

[0255] {Test Example 11}

[0256] The subject test example is an example of washing for asemiconductor device polished by using an abrasive containing abrasivegrains of manganese oxide of MnO₂, Mn₂O₃, Mn₃O₄, or MnO.

[0257] For the abrasives, solid abrasives similar to samples 81 through84 for test example 8 were used.

[0258] The objects to be processed, of which the top surface layers werea Cu film or an Al film with the thickness of 800 nm, were used similarto works 71 and 72 for the test example 7 (Works 121 and 122).

[0259] The polishing condition was similar to polishing condition 61 fortest example 6 and NHO₃ solution adjusted at pH 2 was supplied on asurface to be polished by the additive feeder 206 in FIG. 5.

[0260] The polished object was washed with a washing fluid at thetemperature of 23° C. for the time of supplying the washing liquid of 1minute (washing conditions 11 through 17) by using a brush scrubber.Subsequently, washing with 0.25% of HF aqueous solution at thetemperature of 23° C. for the supplying time of 20 seconds, furtherwashing with water, and spin drying were applied to the washed object.

[0261] For the test, the top surface layer of the object to be processedwas polished by approximately 200 nm under the above-mentionedconditions and subsequently washed on each washing condition. Then, thedensity of Mn atoms remaining on the surface of the processed object wasmeasured. Additionally, the sheet resistance before and after thewashing was measured so as to calculate the reduction of the filmthickness and evaluate the amount of corrosion due to the washing.

[0262] (Abrasives)

[0263] Sample 121: abrasive grains of MnO₂ (20 wt %), a hold-back agentof ice, none of additive

[0264] Sample 122: abrasive grains of Mn₂O₃ (20 wt % of solid content),a hold-back agent of ice, none of additive

[0265] Sample 123: abrasive grains of Mn₃O₄ (20 wt % of solid content),a hold-back agent of ice, none of additive

[0266] Sample 124: abrasive grains of MnO (20 wt % of solid content), ahold-back agent of ice, none of additive

[0267] (Objects to be Processed) Work 121: Cu (800 nm)/Ta (5 nm)/SiO₂(200 nm)/Si substrate

[0268] Work 122: Al (800 nm)/TiN (5 nm) SiO₂ (200 nm)/Si substrate

[0269] (Washing Conditions)

[0270] Washing condition 11: washing liquid of methyl alcohol (CH₃OH) ,temperature of 23° C.

[0271] Washing condition 12: washing liquid of ethyl alcohol (C₂H₅OH) ,temperature of 23° C.

[0272] Washing condition 13: washing liquid of isopropyl alcohol((CH₃)₂CHOH), temperature of 23° C.

[0273] Washing condition 14: washing liquid of propyl alcohol(CH₃CH₂CH₂OH), temperature of 23° C.

[0274] Washing condition 15: washing liquid of 20 wt % of acetic acid(CH₃COOH) aqueous solution, temperature of 23° C.

[0275] Washing condition 16: washing liquid of 20 wt % of citric acid(C₆H₈O₇) aqueous solution, temperature of 23° C.

[0276] Washing condition 17: only washing with HF aqueous solution(0.25%), temperature of 23° C.

[0277] Washing condition 18: washing liquid of 5 wt % of hydrochloricacid (HCl) +5 wt % of H₂O₂, the balance being water, temperature of 23°C.

[0278]FIGS. 15 and 16 are tables showing the result of the subject testexample. FIG. 15 shows the case where the top surface layer of theobject to be processed was a Cu film. FIG. 16 shows the case where thetop surface layer of the object to be processed was an Al film.

[0279] As referring to FIGS. 15 and 16, in the case of washing condition17 as a comparison, the residual Mn atomic density was equal to or morethan 5×10¹³ atoms/m² for all the abrasives and objects to be processed.On the other hand, in washing conditions 11 through 16 of the subjecttest example according to the present invention, the residual Mn atomicdensity was equal to or less than 3×10¹¹ atoms/m² for all the abrasivesand objects to be processed.

[0280] Also, as referring to FIGS. 15 and 16, the amount of corrosionfor HCl+H₂O₂ on washing condition 18 as a comparison was equal to ormore than 50 nm but the amount of corrosion was 30 nm for acetic acidaqueous solution on washing condition 15 at the maximum, or 10 nm onother washing conditions in the subject test sample according to thepresent invention. Additionally, on washing condition 17 as acomparison, since the amount of corrosion is small but the residual Mnatomic density is large, the abrasive grains of manganese oxideremaining on the surface of the object to be processed cannot be washedsufficiently.

[0281] Therefore, according to the present invention, after asemiconductor device is polished with an abrasive containing abrasivegrains of manganese oxide, the abrasive grains of manganese oxideremaining on the semiconductor device can be eliminated andlow-corrosive washing can be performed for a metal such as Cu and Al,etc., of the semiconductor device in such polishing process.

[0282] The test example 12 of the embodiment according to the presentinvention mentioned below is an example of washing with a washing liquidat high temperature of test example 11.

[0283] {Test Example 12}

[0284] Abrasives, objects to be processed, polishing conditions, andtest methods were similar to those of test example 11.

[0285] Washing conditions were similar to those of test example 11except the temperature of washing liquid of 80° C. (washing conditions21 through 27). For the washing liquid, the washing liquids for testexample 11 through 17 were employed.

[0286] (Washing Conditions)

[0287] Washing condition 21: washing liquid of methyl alcohol (CH₃OH),temperature of 80° C.

[0288] Washing condition 22: washing liquid of ethyl alcohol (C₂H₅OH),temperature of 80° C.

[0289] Washing condition 23: washing liquid of isopropyl alcohol((CH₃)₂CHOH) , temperature of 80° C.

[0290] Washing condition 24: washing liquid of propyl alcohol(CH₃CH₂CH₂OH), temperature of 80° C.

[0291] Washing condition 25: washing liquid of 20 wt % of acetic acid(CH₃COOH) aqueous solution, temperature of 80° C.

[0292] Washing condition 26: washing liquid of 20 wt % of citric acid(C₆H₈O₇) aqueous solution, temperature of 80° C.

[0293] Washing condition 27 (comparison): only washing with HF aqueoussolution (0.25%)

[0294]FIGS. 17 and 18 are tables showing the result of the test example.FIG. 17 shows the case of the top surface layer of the object to beprocessed being a Cu layer and FIG. 18 is the case of the top surfacelayer of the object to be processed being an Al layer.

[0295] As referring to FIGS. 17 and 18, in the case of washing condition17 as a comparison, the residual manganese atomic density was equal toor more than 5×10¹³ atoms/m² for all the abrasives and objects to beprocessed. On the other hand, on washing conditions 21 through 26 of thesubject test example according to the present invention, the residualmanganese atomic density was 5×10¹¹ atoms/m² for all the abrasives andobjects to be processed.

[0296] Therefore, according to the present invention, as the temperatureof the washing liquid is 80° C., the remaining abrasive grains ofmanganese oxide in the polishing process can be washed away moresufficiently. The temperature of the washing liquid is preferably equalto or more than 50° C., more preferably equal to or more than 80° C.,from the viewpoint of the washing ability of the washing liquid.

[0297] As being clear from the above detailed description, according tothe present invention, the abrasives have selectivity for polishingobjects to be processed, and the detachment of the abrasive grains on afixed grindstone of a dress jig can be avoided so as to prevent theobject to be processed from being damaged.

[0298] For example, in the polishing process as a process of fabricatinga semiconductor device, etc., the abrasives have selectivity forpolishing a metal layer, etc., as a conductive layer of thesemiconductor device and an insulation layer, and the detachment of theabrasive grains on a fixed grindstone of a dress jig can be avoided soas to prevent the semiconductor device from being damaged. Furthermore,since the additive is supplied to a polishing apparatus by a routedifferent from the route of the abrasive, a wide variety of dispersingagents for abrasive grains of the abrasive can be selected forpreservation of the abrasive without the consideration of the reactivityof the additive with the abrasive.

[0299] That is, since the additive is preserved in one supply containerand the abrasive is preserved in another supply container and theadditive is supplied to a polishing apparatus by a route different fromthe route for the abrasive, the reaction of the additive with theabrasive in the supply container and the supply route can be avoided andcorrosion in the supply containers and supply routes can be alsoavoided.

[0300] According to the present invention, various metals such as Cu andAl and intermetallic compounds thereof used as a material for wiring ofa semiconductor device, etc., can be polished and the kind of materialscontained in waste in a polishing process can be controlled to beminimum so that the waste can be easily treated.

[0301] In particular, chemically stable metals such as Ir and Ta, etc.,can be polished.

[0302] According to the present invention, the proportion of theabrasive grains contributing to polishing can be raised so as to reducethe amount of waste in the polishing process.

[0303] According to the present invention, the abrasive grains remainingon the processed object can be washed away sufficiently after polishing.

[0304] Although the preferable test examples according to the presentinvention are described above in detail, the abrasives and polishingmethods according to the present invention are useful not only forfabrication of a semiconductor device but also for fabrication of athin-film magnetic head, polishing of a lens, etc., and fabrication of aliquid-crystal panel, fabrication of a plasma display panel, fabricationof an exposure mask, and polishing for metal processing.

[0305] The present invention is not limited to the specificallydisclosed embodiment, and variations and modifications may be madewithout departing from the scope of the present invention.

What is claimed is:
 1. An abrasive comprising: abrasive grains selectedfrom the group consisting of MnO, Mn₃O₄, and a mixture thereof; and anadditive that comprises NO₃ ⁻.
 2. An abrasive comprising: abrasivegrains selected from the group consisting of MnO, Mn₂O₃, Mn₃O₄, and amixture thereof; and an additive that comprises H₂O₂.
 3. An abrasivecomprising: abrasive grains selected from the group consisting of MnO,MnO₂, Mn₂O₃, Mn₃O₄, and a mixture thereof; and an additive thatcomprises at least one organic acid selected from the group consistingof gluconic acid, ortho-methylbenzoic acid, citric acid, malonic acid,and acetic acid.
 4. A polishing method of polishing an object with anabrasive that comprises abrasive grains, comprising the step of: mixingan additive with the abrasive, wherein the abrasive grains are selectedfrom the group consisting of MnO, Mn₂O₃, Mn₃O₄, and a mixture thereof;and the additive comprises NO₃ ⁻.
 5. The polishing method as claimed inclaim 4, wherein the object is selected from the group consisting of Si,W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO, MO₂N, Ru, RuO, Pd, Hf,Ta, TaN, WN, Ir and IrO.
 6. A polishing method of polishing an objectwith an abrasive that comprises abrasive grains, comprising the step of:mixing an additive with the abrasive, wherein the abrasive grains areselected from the group consisting of MnO, MnO₂, Mn₂O₃, Mn₃O₄, and amixture thereof; and the additive comprises H₂O₂.
 7. The polishingmethod as claimed in claim 6, wherein the object is selected from thegroup consisting of Si, W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO,Mo₂N, Ru, RuO, Pd, Hf, Ta, TaN, WN, Ir and IrO.
 8. A polishing method ofpolishing an object with an abrasive that comprises abrasive grains,comprising the step of: mixing an additive with the abrasive, whereinthe abrasive grains are selected from the group consisting of MnO, MnO₂,Mn₂O₃, Mn₃O₄, and a mixture thereof; and the additive comprises anorganic acid.
 9. The polishing method as claimed in claim 8, wherein theorganic acid is at least one organic acid selected from the groupconsisting of gluconic acid, ortho-methylbenzoic acid, citric acid,malonic acid, and acetic acid.
 10. The polishing method as claimed inclaim 8, wherein the object is selected from the group consisting of Si,W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO, MO₂N, Ru, RuO, Pd, Hf,Ta, TaN, WN, Ir and IrO.
 11. A polishing method of polishing an object,comprising the steps of: solidifying an abrasive that comprises abrasivegrains selected from the group consisting of MnO, MnO₂, Mn₂O₃, Mn₃O₄,and a mixture thereof; and polishing the object with the solidifiedabrasive.
 12. The polishing method as claimed in claim 11, wherein thestep of solidifying the abrasive comprises cooling and coagulating ofthe abrasive.
 13. The polishing method as claimed in claims 11, whereinthe object is selected from the group consisting of SiO₂, polysilicon,W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO, Mo₂N, Ru, RuO, Pd, Hf,Ta, TaN, WN, Ir and IrO.
 14. The polishing method as claimed in claim11, wherein the abrasive comprises an additive and the additivecomprises one of NO₃ ⁻, potassium phthalate, and an organic acid. 15.The polishing method as claimed in claim 14, wherein the abrasivefurther comprises an additive that comprises one of an inorganic acid,potassium phthalate, an organic acid, and H₂O₂.
 16. The polishing methodas claimed in claim 14, wherein the object is selected from the groupconsisting of W, Al, Cu, Ti, TiN, Cr, Co, Fe, Ni, Nb, Mo, MoO, MO₂N, Ru,RuO, Pd, Hf, Ta, TaN, WN, Ir and IrO.
 17. A washing method of washing anobject polished with an abrasive that comprises abrasive grains selectedfrom the group consisting of MnO, MnO₂, Mn₂O₃, Mn₃O₄, and a mixturethereof, wherein the polished object is washed with a washing liquidthat comprises one of an organic acid and a lower alcohol.
 18. Thewashing method as claimed in claim 17, wherein a temperature of thewashing liquid is equal to or more than 50° C.